Process for producing heat-insulating boards from fibrous material.



. Ito Drawing.

tea a. LAPPEN, or Winona, nannsom, assumes no UNION Finns COMPANY,

' or WINOHA, mmnnso'ra, a cannon or mmnnsora.

' rcnss Eon Penn-acme nna'r-msunerme noenns mom mesons a TEEIAL.

-Material, of which the following is a'speci- I fication.

My invention relates to an improved process for producing heat insulating boards from fibrous material.

Its object is to increase the efficiency with which such boards arefelted with a minimum amount of manipulation.

My process may be applied to any of the vegetable fibers used in the manufacture of insulating boards, such for example as flax,

hemp, jute, cereal "straws or to a mixture of such materials. I

It has heretofore been deemed essential in producing a self-sustaining, long fiber felt for. heat insulating purposes, to intertangle or felt'the fibers by hand while submerged in water. My primary purpose is to obviate the necessity for such submersionand hand-puddling. I also succeed by the use of my improved process in producing a satisfactory insulating board with a smaller percentage of the long and expensive fibers, such as those of flax, jute or hemp, than was formerly considered necessar %hether a single species of raw fiber or a mixture of fibers be used, I prefer to first cook the stock in a digester with an alkaline or similar chemical solution. The digester commonly used in paper making is satisfactory for this purpose, but the alkaline solution may be much weaker and the stock should not be reduced to a pulp. The

cooked stock, having been dumped from the digester, is drained and is preferably washed to remove the alkali, gums and other readily soluble residuum. While this cooking is. desirable, I have found that a satisfactory board may be produced from uncooked stock. if the materials are thoroughly mixed before applying the jets of water hereinafter described. The stock, whether cooked or uncooked, is then, in a moist condition, spread upon an apron or conveyer having a foraminous or slatted bottom adapted to permit the quick drainage of water therefrom. One or more series Specification of I ietters Patent.

\ Application madam-i136, 1915. Serial Ito. 281,881.

E. LArPEN, a

enormous number of minute air cells and Patented Sept. 2%, 1915.

of jets of water, under pressure, are applied .yertically to the stock while the apron or the Jets are moved horizontally. In practice I prefer to move the apron while the jets remaln stationa y- The effect of these jets is to level and make uniform the thickness of the layer of fibrous material passing beneath them, reducing. the irregular tangles or lumps which are usually found in the stock, and also to intermesh and felt the fibers into a mat of substantially uniform consistency. The water applied in ets, as above specified, quickly drainsoff t rough the apertures in the apron, so that the stock is not immersed as has heretofore been the common practice. I have found that these vertical jets of water, acting upon the horizontally moving layer of stock, have upon the longer fibers very much the effect of needles, which drive and interlace such long fibers quite uniformly through the mass in a manner which produces a coherent and homogeneous felt. After the stock has been thus treated,'it is thoroughly compressed into sheets by any suitable means, such as tampers, rolls or the like, and when so compressed is dried, the result being a board of substantially uniform texture, which, while self-sustaining and tough, is filled with an is of high insulating value.

Practical tests have demonstrated that if a given fibrous material, or mixture of and also, it is believed, produces-from a 100 given mixture of fibers a stronger, more uniform and eflicient insulating board than has heretofore been produced from the sameingredients.

Having described my invention, what I 105 I claim as new and desire to protect by Letters Patent is: i

1. The process of felting fibrofis materials, which ;consists in applying jets of water under pressure to a layer of stock, 110

while the stock is moved beneath the iets,

' and then draining the water from the stock.

.3. The process of 'manufacturing' selfsustaining boards from fibrous material,

which consists infirst spreading the stock upon a platform provided with drainage facilities,- second, in applying to'said fibrous material a pluralit of jets of water under pressure and allowing said water to escape, While the platform or jetsare moved in a substantially horizontal plane, third, in

compressing said stock and finally in drying the same.

-In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

- JAMES E. LAPPEN. Witnesses;

A. S. Mona, J. J. BROWN. 

